miles an hour in beating to windward. Since 1876 many catamarans of various forms have been built, most of them having rigid connections, which in smooth water are well enough, but in rough water too much strain is imposed by not allowing each hull to pitch independently of the other. Within a few years, steam has been applied for the propulsion of a double-hulled vessel, both in this country and in England, but in neither case was a greater speed obtained than in ordinary vessels.

CHEMISTRY. Chemical Philosophy. The second report of the Committee of the British Association on Chemical Nomenclature, made to the Montreal meeting, contains tables showing what different names the same substance has received, and to what different substances the same name has been given by the chemists of different countries, and illustrating other `variations in nomenclature that have prevailed. The report says that the usefulness of any system of nomenclature depends on its permanence. Curiously enough, the tables show that where names have been adopted, supposed to represent in some way the chemical constitution of bodies, they have not, as a rule, been adhered to, the advance of knowledge necessitating a change of opinion, while names which took no account of such change of opinion have endured. As a rule, those names are to be preferred which have shown most vitality, and have led to no ambiguity. Where there are two compounds composed of the same elements, the terminations " ous and "ic " should be employed. The prefixes "proto and "deuto," introduced by Thomas Thomson, were intended to mark the compounds in a se

ries, not the number of atoms in a molecule. Where retained, this use only should be made of them. The conclusion of the report is in favor of retaining names of substances in common use rather than to change them for names indicating constitution, which might again be found to require alteration in accordance with some new view on the subject.

The atomic theory has been set in a new light by the researches of Mendelejeff and Lothar Meyer, who, inquiring whether some relations might not exist between the atomic weights of the several elements and their chemical and physical properties, succeeded in tracing an apparent simple relation between the atomic weights and the specific volumes of a considerable number of them, which, although it was not established as to all the elements, incited to further investigation. By various corrections in estimating the atomic weights of a few elements, and the discovery of new substances which fitted into vacant places in the series, the scope of this relation has been extended so as to include fifty-one of the elements, and chemists feel authorized to regard it as a general law.

If all the elements, after hydrogen, with which the law has been verified, are arranged in the order of their atomic weights, they will be found to divide themselves into two kinds of periods or groups: the smaller periods, of which there are two, including seven elements each, and the larger periods, seventeen elements each. The grouping and the distinction of the periods are based upon and justified by the fact that the several members of a single period show no similarity or community of properties and chemical character with one another; but

after that period closes, another period begins, the several members of which show an unmistakable parallelism with the corresponding members of the previous period. Arranging the periods in parallel columns, we shall find that the elements standing on the same horizontal line in every case exhibit similarities in chemical and physical character, and would be at once recognized as allied with one another. This is shown by the following table of the periods, which we take from an article by Victor Meyer in the "Deutsche Rundschau":

LARGE PERIODS.

9 Magnesium. 11 Aluminum.

28

24

Calcium

40

Strontium

Scandium

69.6 Lanthanum ..

188.5

Nitrogen 14 Phosphorus... 81 Oxygen. 16 Sulphur Fluorine......... 19 Chlorine...

...........

The only seemingly exceptional case observable here is in the position of carbon and silicon, whose relationship to titanium and zirconium on the one side, and to tin on the other, is indicated by the dotted lines; but it will also be noticed that the symmetry of the table is still perfect. The first line, it will be observed, contains the five alkali metals-lithium, sodium, potassium, rubidium, and cæsium-between which relationships had already been recognized in their constituting a double triad, and which are known as the most electro-positive of all the elements; while the last line contains the four extremely electro-negative halogens-elements exhibiting quite as striking similarities in all properties with one another as those of the first line. Similar curious relations may be detected in the elements represented in the other lines, and a gradation of electro-chemical properties observed down the columns. When the table was first made, there were two more gaps in it than now appear. They were filled by the discovery of scandium by Nilson, and of gallium by Lecoq de Boisbaudran, with atomic weights fitting them to places that were indicated for new elements, and possessed properties, as determined by experiment, which corresponded with those which Mendelejeff had predicted that the elements that should occupy these places should possess.

Investigating the conditions of the color of chemical compounds, Professor Carnelly has found them dependent on three circumstances, the first two of which were previously determined by Ackroyd-1, temperature; 2, the

quantity of the electro negative element present in the binary compound; and 3, the atomic weights of the constituent elements of the compounds. The color passes, or tends to pass, through the chromatic scale-white or colorless, violet, indigo, blue, green, yellow, orange, red, brown, and black-either by rise of temperature, by increase of the quantity of the electronegative element in a binary compound, or with increase of the atomic weights of the elements A, B, C, etc., in the compounds Ax Ry, Br Ry, Cz Ry, etc., in which R is any element or group of elements; while A, B, C, etc., are elements belonging to the same sub-group of Mendelejeff's classification of the elements. Only sixteen exceptions, or four per cent., were met in four hundred and twenty-six cases in which the third of these rules was applied.

Prof. Frankland, opening a discussion in the British Association on "Chemical Changes in their Relation to Micro-Organisms," thus defined the distinction between animal and vegetable organisms: A plant is an organism performing synthetic functions, or one in which those functions greatly predominate; it transforms actual into potential energy. An animal is an organism performing analytical functions, or one in which these functions greatly predominate; it transforms potential into actual energy:

All micro-organisms appear to belong to the second class. There is no break in the continuity of chemical functions between micro-organisms and the higher forms of animal life. It is true, there are apparently sharp distinctions between them. The enormous fecundity of micro-organisins and their tremen

dous appetites seem to separate them from the higher forms of animals, but this distinction is only comparative. It must be borne in mind that an animal like a sheep, for example, converts much of its food into carbonic acid, hippuric acid, and water, thus utilizing the whole of the potential energy, while the micro-organism, as a rule, utilizes only a small portion. Those micro-organisms which have been studied produce, like the higher animals, perfectly definite chemical changes. Principal Dallinger remarked, in reference to the attempted distinction between the lower animal and vegetable forms, that in following out the life-history of certain monads he had used a nutritive fluid containing no albuminoid substances, but only mineral salts and tartrate of ammonium, and that organisms classed as animals by Prof. Huxley were found to live in that mineral fluid. Bacteria of forms which can not be distinguished by the microscope have very different physiological functions. They can be modified physiologically, but not at all readily morphologically. By a slow change it is possible completely to reverse the conditions of the environment of the bacterium without changing its form.

In a special discussion in the British Association on "The Constitution of the Elements," Prof. Dewar remarked that Deville has shown, by his researches on dissociation, that in compound substances there is an equilibrium between decomposition and recomposition, this balanced relation changing with the temperature. The breaking up of the iodine molecule, effected by Victor Meyer, is a decomposition of elementary matter, but, owing to the rapid recomposition, there seems no hope of isolating atomic iodine at low temperatures. The vapors of potassium and sodium have different densities at different temperatures; probably, also, their molecules consist of two atoms at lower and of one atom at higher temperatures. More exact determinations are needed of those substances which exhibit a variable vapor density. The evidence afforded by spectral analysis proves that oxygen and nitrogen have two spectra, and therefore probably different molecules at different temperatures. Hydrogen has a complicated spectrum under certain conditions. Mr. Lockyer has proved that the identity of certain "basic" lines of different elements, such as iron and calcium, is not due to impurity, but the greater dispersion of more powerful instruments has shown that the coincidence of these lines is only apparent, and not absolute. The differences observed in some of the spectral lines of a single element in the sun might be accounted for not by the decomposition of the "element" into simpler matter, but by great differences of level in the luminous vapor. Prout's hypothesis, that the atomic weights of the other elements are multiples of that of hydrogen, has no basis in experimental fact. Prof. Wolcott Gibbs remarked upon the probability that what is generally regarded as a

simple molecule, such as sodium chloride, consists in the solid state of several hundreds of atoms, and that the salt undergoes, in solution, a kind of molecular dissociation. Very complex molecules, such as those acids he had prepared containing many molecules of the oxides of molybdenum, vanadium, barium, etc., are probably derived by substitution from what are called simple molecules, but which are really composed of a great number of atoms.

Chemical Physics.-Troost has recently shown that oxygen gas is capable of passing through silver at a red heat, in the same manner as hydrogen behaves with platinum and iron. A tube of pure silver was inclosed in a platinum cylinder, and the whole heated in the vapor of boiling cadmium. On exhausting the silver tube with a Sprengel pump, and passing oxygen into the space around it, the gas was found to enter at a rate corresponding to 1.7 litre per hour for each square metre of surface exposed. On passing air instead of oxygen into the outer chamber, oxygen with only a trace of nitrogen was found in the interior, but the rate of transfusion was diminished nearly one half. Instead of exhausting the tube, it was found necessary only to pass through it slowly a stream of some other gas, such as carbon dioxide; but this considerably lessened the rate of transfusion. The oxygen was replaced by other gases, such as carbon dioxide, carbon monoxide, and nitrogen, but they passed through the walls of the tube with extreme slowness. The author suggests that this property of silver may some time be utilized to extract oxygen direct from the atmosphere.

W. Spring has investigated the cause of the different specific gravities of one and the same metal according as it has been cast, rolled, drawn into wire, or hammered; whether the difference observed proves a real condensation of the matter under the action of pressure, or is merely due to the expulsion by pressure of gases which have been occluded when the ingot was cast. According to well-known researches, metals, such as platinum, gold, silver, and copper, which have been proved to occlude gases on fusion, and to let them escape incompletely on solidification, are precisely those which are most increased in their specific gravity by pressure. He has submitted to pressures of about 20,000 atmospheres, metals which possess this property either not at all or to a very trifling extent, and he finds that though a first pressure produces a slight permanent increase of density, its repetition makes little difference. Hence the density of solids, like that of liquids, is only really modified by temperature. Pressure effects no permanent condensation of solid bodies, except as they are capable of assuming an allotropic condition of greater density. The limit of elasticity of a solid body is the critical moment when the matter begins to flow under the action of the pressure to which it is submitted, just as, for example, ice at or below 0° C. may be liquefied

by strong pressure. A brittle body is simply one which does not possess the property of flowing under the action of pressure.

M. Alexeyeff, a Russian, regarding gravitation, cohesion, and chemical affinity as three degrees of the same force, asks which of the last two is manifested in solutions, and declares in favor of cohesion. The simplest cases of solutions are, in fact, those where there is no chemical affinity between the bodies dissolving and dissolved. The solution of gases in solid bodies is quite analogous to imbibition by solids of liquids, and the much greater solubility of gases in liquids may be easily explained by the easier penetration of gases between the molecules of a liquid. The law of solubility given by Dalton is in perfect agreement with the supposition that the dissolved gases maintain their own aggregation when dissolved. The same is true with regard to solutions in liquids.

New Substances.-Under the title of "Complex Inorganic Acids," Prof. Wolcott Gibbs refers to a class of compounds of molybdic, tungstic, and vanadic acids with other mineral acids, giving rise to substances of very complicated atomic constitution. At least ten series of phospho-tungstates have been described, and the phospho-molybdates are equally numerous and have a similar range. Combining other acids, we may have a great variety of these compounds; and many of the salts are very beautiful. Compounds have also been prepared in which the methyl, ethyl, and phenyl derivatives of phosphorous and hypophosphorous acids occur. As an instance of the extreme complexity of some of these compound acids, Prof. Gibbs gave the body 60 WOs, 3 P2Oь, V2O, VO2, 18 BaO, +150 Aq., which has the enormous molecular weight of 20,066. From the analogy in constitution between phthalic and ortho-sulpho-benzoic acids, Prof. İra Remsen inferred that the latter might act upon phenols in the same way that the former does, and that thus compounds analogous to the phthaleins might be obtained. Experiment confirmed this. A mixture of potassium orthosulpho-benzoate and resorcin heated with sulphuric acid and treated with caustic soda, and similar processes with derivative and substitution products of sulpho-benzoic acid, gave rise to a series of products for which the designation of sulphon-phthaleins is proposed.

M. Struve, of Tiflis, in the "Journal" of the Berlin Chemical Society, describes a form of fermented milk, called kephir, which occupies a similar position in the dietary of the northern Caucasus with koumiss in southeastern Russia. It is prepared by fermenting either sheep's, cow's, or goat's milk in leathern bottles with what are called kephir-grains, a ferment the origin of which is unknown. The milk becomes very much changed during the process. The kephir-grains are also reproduced, but are removed after a certain stage of fermentation has been reached, and may be preserved by drying in the sun, to be used again in promot

The 33-11 per cent. of insoluble matter seems to be the only active part of the kephir-grains; and its activity is attributed to Saccharomyces mycoderma.

W. Kühne and R. H. Chittenden, following up an idea that was suggested to them by some of the reactions of hemialbumose that that substance might be a mixture, have obtained from it, by treatment with sodium chloride and acids, four new forms of albumose, which they designate as follows:

No. I. Precipitated by excess of sodium chloride, soluble in cold and hot water: protalbumose.

No. II. Precipitated by excess of sodium chloride, insoluble in cold and boiling water; but, on the other hand, soluble both in strong and dilute solutions of sodium chloride: deuteroalbumose.

No. III. Similar to No. II, but insoluble in solutions of sodium chloride: heteroalbumose.

No. IV. Not precipitated by excess of sodium chloride, but precipitated by sodium chloride and acids; soluble in water: dysalbumose.

The "hemi" of the name is retained in each case. While these several forms of albumose differ somewhat in their general properties, the percentage composition of the various products shows a remarkable degree of uniformity. The existence of these substances and the differences in their properties throw some light on the facts, previously determined, concerning "soluble" and "insoluble" albumose, and that of the contradiction regarding the precipitability of albumose in part by sodium chloride alone, and in part only by the united action of an acid. What was previously designated "insoluble" hemialbumose consists of hetero albumose, soluble only in boiling dilute sodium chloride, which, after once being boiled, separates in great part on cooling. "Soluble" hemialbumose corresponds to both protalbumose and deuteroalbumose, or to a mixture of both those bodies. When protalbumose is obtained free from deuteroalbumose, it is at once evident, from the fact that the latter can not be precipitated by sodium chloride alone; but since we have become familiar with heteroalbumose, it is also clear that in the majority of cases the precipitate obtained by simple addition of sodium chloride can not be pure protalbumose, as there remains mixed with it a portion of heteroalbumose, which can be separated by dialysis. The earlier statements regarding the turbidity and precipitation of hemialbumose by neutralization, as also its precipitation, after the manner of albuminates, from solutions ori